1. Technical Field
This invention relates to the cutting of food product with hydraulic food cutting devices. In particular it relates to a tensive cutting assembly for cutting food product.
2. Background of the Invention
A variety of xe2x80x9chydro-cuttingxe2x80x9d devices for cutting food product into slices and sticks are known in the art and typically include a cutting assembly comprising a plurality of sharpened cutting knives arranged and held in a stationary array with a means to propel the food product through the knife array. The food product may be conveyed through the knife array by suspending the food product in a fluid stream, such as water.
The typical hydraulic food cutting apparatus in use today has a receiving tank filled with a hydraulic carrier fluid, usually water, into which food product is dumped. A food pump draws its suction from the receiving tank, and pumps carrier fluid and the suspended food product from the tank into an inlet tube which aligns the food product before impact with a cutter assembly. Cutter blade assemblies include typically a frame and a stationary knife array typically including a plurality of individual knife blades mounted in a parallel and converging sequence to each other. If the food product is to be cut into slices, only a single such array need be utilized. However, if the food product is to be cut into sticks, such as potatoes for French fries, two such arrays are utilized with the knives in one array extending generally perpendicular to the knives in the other array.
Cole, et.al., U.S. Pat. No. 5,343,623 Knife Assembly for Cutting a Food Product, discloses a knife blade for use in a cutting assembly comprising a plurality of sharpened cutting knives arranged and held in a stationary array. Each blade includes a sharpened cutting edge, and holes adapted to accommodate a means for attaching the knife blades to a mounting member. The centers of the mounting holes lie in the plane of the cutting edge. The plurality of sharpened knife blades are mounted in the knife assembly so that a tension force is exerted on the knife blades in the plane of the cutting edge. The cutting edges of knives in an array are located in a common plane.
According to the present invention a tensive cutting assembly includes a tensionable cutting member formed of a strip of material, typically, metal which is formed having a serpentine configuration. The tensionable cutting member is removably and interchangeably mounted on a tensive cutting head. The tensive cutting head includes an aperture formed through its cross section for passage of food product during the cutting process. The tensive cutting head includes first and second opposing head members, the distance between which is adjustable. The tensive cutting head may be configured having at least one return about which the bend or bends of the tensive cutting member is positioned. The ends of the tensive cutting member are secured in one or more clamping members. Tension is applied to the tensive cutting member by increasing the distance between the first and second opposing head members along a plane that lies substantially coplanar to the face of the tensive cutting head and perpendicular to the bearing faces of the returns.
One embodiment of the invention includes a plurality of returns divided into first and second sets of returns, the first and second sets are divided into opposed pairings of returns. The first set of returns are formed on or attached to the face of the first opposing head member and the second set of returns are formed on or attached to the face of the second opposing head member. The returns are arranged sequentially, with an equal distance typically being observed between each of the sequential returns. Opposing sets of returns are offset laterally from one another a distance substantially equal to the distance between two sequential tensionable cutting member leg segments. This configuration allows the tensionable cutting member to be fit over the opposing sets of returns in a manner that permits a substantially parallel arrangement of the tensionable cutting member leg segments. The distance between sequential returns determines the distance between leg segments and therefore a cross-sectional dimension of the cut food product.
Each return is configured having a bearing face about which the bend of the tensionable cutting member is placed. In one embodiment of the invention, the bearing face of the return is substantially perpendicular to the face of the tensive cutting head and the plane on which the first and second opposing head members are driven apart. This feature allows the tensive cutting member to be tensioned in such a manner that the tension across the entire width of the tensive cutting member is substantially equal. This arrangement effectively eliminates the creation of stress risers in the tensive cutting member that may otherwise be propagated in devices that tension a blade or cutting member unequally across the width of the blade or along a single edge. The bearing face may also include a low friction surface against which the tensionable cutting member is fit and tensioned. In the preferred embodiment of the invention, the height of the bearing face should be substantially equal to or greater than the width of the tensionable cutting member so that, as the tensionable cutting member is tensioned, substantially equal tensile forces are established across the width of the tensionable cutting member.
The tensive cutting head may be machined of type 17-4 PH stainless steel, although other materials and forming methods known to those skilled in the art may be employed to practice the present invention.
The tensionable cutting member includes a strip of material formed having at least two leg segments and at least one bend connecting the two leg segments. In one embodiment of the invention, the tensionable cutting member is formed having a plurality of leg segments and a plurality of bends producing a continuous and generally serpentine configuration. Either the first edge or the second edge of the tensionable cutting member may be employed as the cutting edge of the tensionable cutting member. The cutting edge of the tensionable cutting member may be unsharpened and the edges may be rounded or otherwise treated or dressed in order to eliminate edge and surface irregularities.
The tensionable cutting member may be formed of a strip of sheet metal having a thickness of 0.005 inches to 0.0015 inches and a width of 0.375 inches to 0.625 inches. In one embodiment of the invention, the tensionable cutting member is formed of a hardened 301 stainless steel having a thickness of 0.008 inches and a width of 0.50 inches. The material used to form the tensionable cutting member should exhibit adequate tensile strength to perform as a tensionable cutting member and adequate ductility to allow its serpentine configuration. The material should also exhibit a yield strength less than the tensile strength. The tensionable cutting member may be formed of a strip of sheet metal having a tensile strength of 175,000 psi to 275,000 psi and a yield strength of 80,000 psi to 180,000 psi. In one embodiment of the invention, the tensionable cutting member is formed from a hardened type 301 stainless steel having a tensile strength of approximately 185,000 psi and a yield strength of approximately 140,000 psi. Materials having compositions or properties similar to the hardened 301 series stainless steel, or a type 17-4 PH stainless steel, are known to those skilled in the art and may be employed in the present invention as a tensionable cutting member.
In one embodiment of the invention the tensive cutting assembly includes a first tensionable cutting member mounted to the first and second opposing head members, presenting a first cutting array and a second tensionable cutting member mounted to a third and a fourth opposing head members on the second face of the tensive cutting head, presenting a second cutting array. The second cutting array is commonly rotated typically at 90xc2x0 to the first cutting array. This embodiment of the tensive cutting assembly, when employed within a hydraulic cutting device, renders cut food product having stick configuration.
In another embodiment of the invention, the tensive cutting head may be configured having only a single or first array, which will render cut food product having a slabbed configuration.
The tensive cutting assembly also includes a cutting member tensioning device for applying a tensive force along the length of the tensionable cutting member. Alternate means for tensioning the tensionable cutting member may include means integral to the tensive cutting head such as mechanical means such as screws, machine heads, levers or levered cams, or hydraulic means. Alternately, a cutting member tensioning device may be employed which is attached to the tensive cutting head only during tensioning, and releasable after the tensionable cutting member is tensioned and the ends of the tensionable cutting members are secured. In one embodiment of the invention, tensioning is achieved using a pair of tension adjustment screws which adjust the distance between opposing head members and therefor between opposing sets of returns. The tension adjustment screws project through and engage a threaded aperture in the first opposing head member, with the second or distal ends of the tension adjustment screws being insertable in a pair of holes located in the second opposing head member. As the tension adjustment screws are advanced in their threads, a force is exerted along a tension vector increasing the distance between the first and second opposing head members, thereby tensioning the tensionable cutting member. This method of blade tensioning is capable of achieving tensive forces along the tension vector in the range of 100,000 psi to 200,000 psi.
The tensive cutting assembly may also include a breakage detecting device for detecting breakage during use of the tensive cutting assembly. The device for detecting breakage of a tensionable cutting member includes a fluid containment cell and a pressure release mechanism. The tensionable cutting member failure detecting device also includes a fluid pressure source fluidly connected to the fluid containment cell. The connector for connecting the fluid pressure source to the fluid containment cell may include a variety of mechanical connectors including threaded fittings, compression fittings or quick disconnect type fittings.
The fluid containment cell may be configured as a cylinder formed in either the first or the second opposing head members of the tensive cutting head. The pressure release mechanism includes a stop which is configured to compressively mate against a seat formed in an aperture located in an end of the cylinder. When the stop is compressively mated against the seat, fluid will not escape from the fluid pressure chamber and pressure may be maintained within the chamber. In this embodiment of the invention, the stop is configured as a sliding stop which opposes the seat and which cooperates with a compressive member for holding the sliding stop against the seat of the fluid pressure chamber and sealing the fluid pressure chamber.
In the event that the compressive force against the sliding stop is relieved, fluid escapes from the fluid pressure chamber causing the fluid containment cell to depressurize. Because the compressive force against the seat is created by the tensile forces exerted against the tensionable cutting member by the tensioning screws, in the event of a failure or breakage of the tensionable cutting member, pressure escapes from the fluid pressure chamber.
The tensionable cutting member failure detecting device also includes a pressure sensing device fluidly connected to the fluid containment cell for sensing a decrease in pressure in the system. The pressure sensing device may be configured as a pressure switch which includes a set of electrical contacts which are activated by a change in pressure against a diaphragm. The opening or closing of the contacts in response to pressure against the diaphragm may signal a variety of other devices including controllers, switches, line switchers, relays and/or motors.
The tensionable cutting member failure sensing device may also include a flow regulator for regulating fluid pressure from the pressure source to the fluid containment cell and a pressure gauge for indicating system pressure.
Other advantages will become apparent to those skilled in the art from the following detailed description read in conjunction with the appended claims attached hereto.